Podcaster: Richard Drumm

Title: Famous Women Astronomers – Annie Jump Cannon

Organization: 365 Days Of Astronomy


Hosted by podcast editor Richard Drumm.

She was born on December 11, 1865 in Dover, Delaware. Her parents were Wilson Cannon and Mary Jump. Her father was a shipbuilder and also a state senator, and her mother is the one who got her interested in astronomy and mathematics.

She attended what will later be known as Wesley College in Delaware, and then transferred to Wellesley College in Massachusetts.

That’s not confusing or anything, is it?

Bio: Richard Drumm is President of the Charlottesville Astronomical Society and President of 3D – Drumm Digital Design, a video production company with clients such as Kodak, Xerox and GlaxoSmithKline Pharmaceuticals. He was an observer with the UVa Parallax Program at McCormick Observatory in 1981 & 1982. He has found that his greatest passion in life is public outreach astronomy and he pursues it at every opportunity.

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This is the 365 Days of Astronomy Podcast. Today we bring you another new episode in our new series, Famous Women Astronomers, with the story of Annie Jump Cannon.

She was born on December 11, 1865 in Dover, Delaware. Her parents were Wilson Cannon and Mary Jump. Her father was a shipbuilder and also a state senator, and her mother is the one who got her interested in astronomy and mathematics.

She attended what will later be known as Wesley College in Delaware, and then transferred to Wellesley College in Massachusetts. 

That’s not confusing or anything, is it?

Hmmm… Anyway.

While at Wellesley she contracted scarlet fever. As a result of that infection migrating up her eustachian tubes and infecting her inner ears, she was mostly deaf. 

In later years she used an Acousticon, an early, battery powered, electric hearing aid, and with it she communicated with colleagues and even maintained an active interest in local theater.

After being the valedictorian and graduating from Wellesley in 1884 she went home to Delaware.

For a decade.

But she didn’t sit on her hands, no no. She acquired skills in the new technology of photography, taught and tutored students and performed community work.

She took a trip to Spain and her memories of the trip were published as a pamphlet that was distributed at the World’s Columbian Exposition in 1893.

Her mother died unexpectedly the next year, 1894. Partly as a result, she contacted her old professor from Wellesley, Sarah Frances Whiting, and was hired as a physics teacher there at Wellesley.

She started her graduate courses there at Wellesley, too, in 1895, and also enrolled at Radcliffe College in order to use the telescope at the Harvard College Observatory, the HCO. 

Radcliffe was a sister institution to Harvard College, so its students had access to Harvard’s equipment.

Her Wellsley professor Whiting had studied under Harvard’s professor Edward Pickering, the director of the HCO. 

With that personal connection, her significant academic credentials and telescope operation experience, in 1896 she was hired by Pickering as an assistant at the HCO, and became a member of the Harvard Computers. 

Meanwhile she continued her studies, and in 1907 she attained her Master’s Degree from Wellesley.

Pickering had hired his so-called “computers” for the express purpose of completing the Draper Catalogue of stars. 

The men at the Observatory operated the telescope, exposed the glass plates to the sky and performed the chemical processing of the exposed plates afterward.

The women examined the plates and analyzed the spectra of the stars in the daytime. In the winter they got to work in the heated office, not a cold observatory. 

I think the women got the better job.

Too bad they didn’t get commensurate pay!

The spectra were obtained by having an objective prism in front of the telescope’s objective lens, which spreads the light of every star in the field of view into a spectrum.

This way a hundred spectra could be created with a single exposure of a plate. 

She could identify a spectrum in as little as 20 seconds, and identified around 358,000 stars during her long career. She was by far the best spectrum analyzer in the world.

When Miss Cannon arrived at Harvard the classification of stars that was used was A, B, C, D and so on, based on the strength of the Hydrogen line in the spectrum.

However, Annie got the brilliant idea to use a different criterion, the strength of the Balmer spectral lines, one which later was discovered to directly relate to the star’s surface temperature. 

She kept the original alphabet designations, though, but with a new arrangement. Thus we arrived at the now-familiar OBAFGKM classification and it’s “Oh be a fine girl kiss me” mnemonic. 

Her Balmer line-based scheme was officially adopted by the IAU in 1922 and is still used to this day. It’s unlikely that it’ll ever be supplanted.

But it has had some additions over the years.

There are a few additional classifications even redder than M. They are R, N and S. R & N are sometimes called C type and are dim, cool carbon stars, the C coming from the c of carbon.

One of these that I saw, R Leporis, was so red it looked like the taillight of a car! Super pretty!

There are sub-classifications within each class, designated by the numbers 0 to 9, with the higher numbers applied to the cooler stars.

Brown dwarfs are designated by even more spectral classes L, T & Y in order of decreasing temperature. 

Class Y stars are super cool, with a surface temperature less than 800 Kelvin or 980 degrees fahrenheit. They even have spectral lines for water, but at that temperature, I suppose it’s steam…

In addition to the red dwarf categories that were added, there were the luminosity scales borrowed from the MK or Yerkes system that have been added to each of the spectral types.

This scale is represented by Roman numerals like this:

I. Is the supergiants.

II. Is bright giants.

III. Is normal giants.

IV. Is the sub giants. And…

V. Is main sequence dwarf stars, like our Sun.

By the way, Sol, our Sun, is a G2 V class yellow dwarf star.

Now where was I…

Oh yeah! Annie Jump Cannon!

Cecelia Payne described her as the HCO’s “adoptive mother hen” who took many students under her wing, so-to-speak.

I WILL be doing a program on Cecelia Payne-Gaposchkin! 

You can count on it!

While Annie Jump Cannon was the Curator of Astronomical Plates at HCO the team published the 9 volume Henry Draper Catalogue. 

Immediately after that, she embarked on an extension of the catalog. There’s no shortage of stars in the sky!

In 1922 she spent a summer at Harvard’s Arequipa Observatory in Peru, operating the Bruce telescope there and producing many plates for later analysis.

She received honorary doctorate degrees from the University of Groningen and Oxford University.

In 1938 she finally received an official appointment at Harvard as the William C. Bond Astronomer.

She has a lunar crater, Cannon, and an asteroid, 1120 Cannonia, named after her.

She retired in 1940 but continued to work at the Observatory till just before she died, in 1941.

Annie Jump Cannon’s legacy continues with the Annie Jump Cannon Award in Astronomy issued by the AAS. It’s awarded annually to women whose doctoral theses are particularly impactful in the field.

Annie Jump Cannon paved the way for generations of women astronomers, gaining them acceptance and respect with her calm, focused, diligent work and welcoming attitude.

We need more Annie Jump Cannons in our world.

Thank you for listening to the 365 Days of Astronomy Podcast!

End of podcast:

365 Days of Astronomy

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